The Philadelphia man who admitted to calling in a fake report about explosives on a Dallas-Fort Worth-bound airplane that caused the plane to be diverted back to Philadelphia International Airport will write an apology letter to every person on that plane.

Kenneth Smith Jr., 26, pleaded guilty Monday to malicious false information about an explosive, and false information and hoaxes, according to a press release from the U.S. Attorney’s Eastern District of Pennsylvania Office.

Smith, a pizza cook, faces up to 15 years in prison, up to $500,000 in fines and restitution when he is sentenced April 16. He already agreed to pay restitution and write an apology letter to every passenger who was on Flight 1267 when it was delayed. He also agreed to reimburse the emergency response costs, prosecutors said.

Flight 1267 was turned around shortly after taking off from Philadelphia International Airport. Sixty-nine passengers and five crew members were on the plane. In a strange twist, the incident happened on Shell's 29th birthday.

Smith’s reasoning for the hoax, according to federal prosecutors, was to “avenge” a woman who was at the time identified as Shell’s ex-girlfriend and Smith’s current girlfriend. Reportedly Shell had posted a compromising photo of the woman on Facebook.

Shell was removed from the airplane in handcuffs. He later wound up making it to Dallas where we was arrested on two outstanding warrants, police said. NBCDFW spoke to Shell in October about the plane hoax and how it derailed his career.